Proof of ion-pair structures in ammonium-based protic ionic liquids using combined NMR and DFT/PCM-based chemical shift calculations

文献情報

出版日 2017-08-09

DOI 10.1039/C7CP04481J

インパクトファクター 3.676

著者

M. Lozynski, J. Pernak, Z. Gdaniec, B. Gorska, F. Béguin

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要旨

The self-assembly of triethylammonium bis(trifluoromethylsulfonyl)imide, i.e. [(C2H5)3NH][TFSI], in chloroform and aqueous solutions has been investigated using 1H NMR spectroscopy and computational (DFT/PCM prediction) methods. We have examined a number of ion pairs formed between the [(C2H5)3NH]+ cation with different conformations of alkyl substituents as well as various dispositions of the multi-site [TFSI]− anion. Based on the agreement between the calculated (DFT) and observed 1H NMR chemical shifts, [(C2H5)3NH][TFSI] in chloroform formed lipophilic complexes with effective N+–H⋯N or N+–H⋯O hydrogen bonding, whereas hydrophilic complexes with Cα–H⋯O and Cα–H⋯F hydrogen bonding are found in aqueous solutions. This study provides a new insight into the self-aggregation of ammonium PILs incorporating the widely used [TFSI]− anion and demonstrates the importance of solvent effects on chemical shifts. The simulations with explicit and implicit dielectric continuum solvents are found to be the most realistic method, yielding a representative ensemble of structures.

掲載誌

Physical Chemistry Chemical Physics

CiteScore: 5.5

自己引用率: 10.3%

年間論文数: 3036

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